A diverse user-group of 6 investigators, comprising four schools at The Johns Hopkins University including the Schools of Arts & Sciences, Engineering, Public Health, and Medicine; as well as the Carnegie Institution for Science, request funds to purchase a Carl Zeiss Lightsheet Z.1 Fluorescence Microscope (LSM). This system integrates an enclosed sealed-box imaging system with: 1) a sample chamber and holder; 2) incubation, CO2, and microfludics; 3) 405nm, 488nm, 561nm, and 638nm lasers; 4) 5X dual illumination optics; 5) detection optics, including a 5X and 20X objectives optimized for whole organism and Clarity imaging; and 6) dual PCO Edge sCMOS cameras. All of these components are integrated, and conveniently accessed/precisely controlled through the Carl Zeiss ZEN 2012 software (Black). This new state-of-the-art workstation will be sited in the Hopkins' Integrated Imaging Center (IIC, http://www.jhu.edu/iic) on the Homewood campus; and will complement other existing fluorescence instruments by filling a unique niche for whole organism imaging (allowing for multi-day time course, dynamic live imaging experiments). It will be particularly useful for Clarity experiments that are not possible using other conventional fluorescence approaches; and will be especially suited to the zebra fish work proposed by two of our users. The IIC is a Homewood campus/Hopkins-wide microscopy resource, jointly supported by the Krieger School of Arts and Sciences and the Whiting School of Engineering (see Toscano & Douglas letterin Letters of Support); and utilized regularly by multiple schools and departments comprising >150 laboratories and >450 users. Our investigators, all well-funded through the NIH, work on a host of diverse basic cell biology, neuroscience, and developmental biology related questions including, though not limited to: cell migration in development and disease; angiogenesis; apoptosis; neural plasticity; and mitochondrial biogenesis. In the requested configuration, the Lightsheet Z.1 will afford our investigators the capability to precisely image multiple fluorophores simultaneously or sequentially at real-time acquisition speeds (30fps); to accurately modulate laser power in order to greatly minimize phototoxicity and photobleaching over multi-day extended time-lapse imaging sessions; and to generate 3D reconstructions of Clarity prepared brains, organs, developing embryos, and cell growth/migration in hydrogels. The new system will be incorporated into the IIC's existing, well established recharge system to ensure recovery of funds for supplies and maintenance; it will be made freely available to all interested users Hopkins- wide through our convenient web-scheduler; and it will be incorporated into the IIC's annual undergraduate/graduate course offerings. (http://www.jhu.edu/iic/academic.htm).